The Edison Electric Institute — whose members generate the bulk of the nation's electricity — and two of its influential CEOs, Exelon's John Rowe and Duke Energy's Jim Rogers, will declare their support Monday, sources said. While Kerry did not name the three oil companies, a source familiar with the negotiations said Shell, BP and ConocoPhillips would back the climate measure.

And why did these folks decide to support the bill? Here's the big payoff:

The bill will preempt both the states' and EPA's ability to regulate greenhouse gases under the Clean Air Act, as long as emitters comply with the standards outlined in the measure. The EPA will monitor and enforce compliance with the law.

That's pretty much been the plan all along: use the threat of EPA action to gain support from Republicans and the business community. It seems to be working on the business community, so the only question left is whether it will work on Republicans. Normally I'd say no, but the threat of EPA action is quite real and might prompt the GOP's business wing to put some serious pressure on them to get this bill passed. That will mean standing up to the "carbon taxes are tyranny" crowd in the tea party movement, but in the past the business wing of the party has usually won these kinds of showdowns. It's still not clear if there's enough time on the congressional calendar to pass a climate bill this year, but at least the odds are now a little better. Kate Sheppard has more details here.